New Delhi, Oct 28 (PTI) The Railways plans to use aircraft-like pressurised coaches in its trains for the Bilaspur-Manali-Leh line along the India-China border, which will be the world's highest rail track, so that passengers do not have breathing difficulties on board.

Aircraft cabins are pressurised because the air is very thin at the altitude planes fly. To prevent complications, the cabins of many aircraft are adjusted to near sea-level pressure, which makes breathing almost the same as at sea level.

At a height of 5,360 metres above the sea level, the 465-km strategically significant line to be built at a cost of Rs 83,360 crore, will see railways' first pressurised coaches which are currently used only in the Quinghay-Tibet Railway Line in China.

"Special pressurised rolling stock to deal with lack of oxygen will have to be used in these trains as passengers might feel uneasy because of the high altitude. These will be like the pressurised cabins used by aircraft to maintain the oxygen levels inside," said Chief Engineer (Construction), Northern Railway, D R Gupta.

The Chinese coaches, manufactured by Canada's Bombardier Inc, which also makes small planes, are specially designed to carry passengers in an oxygen-deficient atmosphere.

In order to do this, the train cars have to be pressurised, to ensure that all of the passengers do not finish their journey with severe cases of altitude sickness.

Gupta explained that in the Tibet train, two kinds of systems are used to maintain oxygen levels - one is through the main controls which maintains standard oxygen levels and gets switched on at high altitude areas and the other is through oxygen ports equipped for each passenger to use when they feel that they lack oxygen.

It is, however, not clear if these coaches will be produced in India or they will be procured from outside.

The Integrated Coach Factory which is in expansion mode is already pepping up to produce both metro coaches as well as coaches for the Ahmedabad-Mumbai bullet train and could be roped in to make coaches for the Bilaspur-Manali-Leh line as well, an official said.

The line, once completed, will connect important locations between Bilaspur and Leh like Sundernagar, Mandi, Manali, Keylong, Koksar, Darcha, Upshi and Karu and other important towns of Himachal Pradesh and Jammu & Kashmir en route.

The project will include 74 tunnels, 124 major bridges and 396 minor bridges, according to the first phase of the survey. Final location survey for the project is currently underway.